2020/8

y2020/p08.py

+import re
+import sys
+
+
+def run(text):
+    acc = 0
+    pos = 0
+    seen = set()
+    instructions = text.splitlines()
+    while pos not in seen:
+        seen.add(pos)
+        inst, n = instructions[pos].split()
+        if inst == 'acc':
+            acc += int(n)
+            pos += 1
+        elif inst == 'jmp':
+            pos += int(n)
+        elif inst == 'nop':
+            pos += 1
+
+        if pos == len(instructions):
+            raise RuntimeError(acc)
+
+    return acc
+
+
+text = sys.stdin.read()
+print(run(text))
+for match in re.finditer(r'(jmp|nop)', text):
+    seen, (a, b) = match.group(0), match.span()
+    pair, = {'jmp', 'nop'} - {seen}
+    var = text[:a] + pair + text[b:]
+    try:
+        run(var)
+    except RuntimeError as error:
+        print(error)